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 A340078 a(n) = gcd(n, 1+A018804(n)), where A018804(n) = Sum_{k=1..n} gcd(k, n). 3
 1, 2, 3, 1, 5, 2, 7, 1, 1, 2, 11, 1, 13, 2, 1, 1, 17, 2, 19, 1, 3, 2, 23, 1, 1, 2, 1, 7, 29, 2, 31, 1, 1, 2, 1, 1, 37, 2, 3, 1, 41, 14, 43, 1, 5, 2, 47, 1, 1, 2, 1, 1, 53, 2, 5, 1, 3, 2, 59, 1, 61, 2, 1, 1, 1, 2, 67, 1, 1, 2, 71, 1, 73, 2, 1, 1, 1, 2, 79, 1, 1, 2, 83, 1, 1, 2, 1, 1, 89, 2, 1, 1, 3, 2, 1, 3, 97, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Antti Karttunen, Table of n, a(n) for n = 1..8191 Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537 FORMULA a(n) = gcd(n, 1+A018804(n)). PROG (PARI) A018804(n) = sumdiv(n, d, n*eulerphi(d)/d); \\ From A018804 A340078(n) = gcd(n, 1+A018804(n)); CROSSREFS Cf. A018804, A340079, A340080. Cf. also A055023, A323071 (similar but different sequences). Sequence in context: A021816 A055023 A323071 * A126773 A326691 A277698 Adjacent sequences:  A340075 A340076 A340077 * A340079 A340080 A340081 KEYWORD nonn AUTHOR Antti Karttunen, Dec 30 2020 STATUS approved

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Last modified July 24 14:15 EDT 2021. Contains 346273 sequences. (Running on oeis4.)